MON1 encodes the Candida albicans ortholog of vacuolar fusion protein Mon1, a conserved MON1/SAND-family longin-domain protein in the fungal MON1 subfamily. By descent from the characterized fungal Mon1 proteins, it is expected to associate with Ccz1 in the Mon1-Ccz1 Rab GEF complex on endolysosomal and vacuolar membranes, where the complex contributes guanyl-nucleotide exchange activity for Rab7/Ypt7-family GTPases and promotes protein delivery to the fungal vacuole.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000329 fungal-type vacuole membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Q5A723 falls in the fungal MON1 subfamily PTHR13027:SF7, and PAINT places the fungal-type vacuole membrane annotation at the fungal PTN000989606 ancestor with Saccharomyces cerevisiae MON1 as experimental seed. Reason: The IBA follows the fungal PAINT node PTN000989606 rather than a pairwise Candida-to-yeast transfer. The placement is consistent with the Q5A723 PANTHER classification and with direct budding-yeast experiments showing that the Ccz1-Mon1 complex binds the vacuole membrane. Retain this as the most specific asserted core vacuolar location. Supporting Evidence: PMID:14662743 Ccz1 and Mon1 form a stable protein complex that binds the vacuole membrane. |
| GO:0003674 molecular_function | ND GO_REF:0000015 | ACCEPT | Summary: CGD's ND row records that no direct Candida albicans molecular function annotation was available at assertion time. Reason: ACCEPT under the ND acceptance rule (projects/NO_DATA.md). The evidence this review cites for the molecular function is inferred (from orthologs, family membership or sequence features) or comes from other species; none of it is literature on this gene product in this species. This was judged from the review's own content during the NO_DATA re-action pass, not from a new literature search. Earlier action: REMOVE. Re-checked 2026-10-31: the GEF papers cited in core_functions (PMID:14662743, PMID:24413168) are on S. cerevisiae Mon1-Ccz1. The gene's notes record PubMed searches that found no C. albicans MON1 paper at all. Supporting Evidence: file:CANAL/MON1/MON1-notes.md No PubMed record was found for `Candida albicans` plus `MON1`, `orf19.8109`, or |
| GO:0005085 guanyl-nucleotide exchange factor activity | IBA GO_REF:0000033 | ACCEPT | Summary: The Mon1-Ccz1 complex acts as the GEF for the late endosomal/vacuolar Rab7-family GTPase, and the PTHR13027 PAINT family places this contributed GEF function on the broad eukaryotic MON1/CCZ1 clade at PTN000315021. Reason: This is the expected catalytic role of a MON1 subunit in the Mon1-Ccz1 complex. Budding-yeast experiments show that Mon1-Ccz1 GEF activity for Ypt7 requires Mon1 residues and is strongest with membrane-anchored Ypt7, and Q5A723 is a member of the fungal PTHR13027:SF7 MON1 subfamily under the PAINTed ancestor. Supporting Evidence: PMID:24413168 Mon1–Ccz1 activity requires residues within the predicted longin domains of both subunits |
| GO:0005575 cellular_component | ND GO_REF:0000015 | ACCEPT | Summary: CGD's ND row records that no direct Candida albicans cellular-component annotation was available at assertion time. Reason: ACCEPT under the ND acceptance rule (projects/NO_DATA.md). The evidence this review cites for the cellular component is inferred (from orthologs, family membership or sequence features) or comes from other species; none of it is literature on this gene product in this species. This was judged from the review's own content during the NO_DATA re-action pass, not from a new literature search. Earlier action: REMOVE. Re-checked 2026-10-31: the papers cited in core_functions (PMID:14662743, PMID:24413168) are on S. cerevisiae Mon1-Ccz1. The gene's notes record PubMed searches that found no C. albicans MON1 paper at all. Supporting Evidence: file:CANAL/MON1/MON1-notes.md No PubMed record was found for `Candida albicans` plus `MON1`, `orf19.8109`, or |
| GO:0005774 vacuolar membrane | IEA GO_REF:0000044 | MODIFY | Summary: UniProtKB-SubCell maps the conserved vacuolar-membrane location of Q5A723 to the generic vacuolar membrane term. Reason: Vacuolar membrane is directionally correct for fungal Mon1, but the accepted PAINT annotation to fungal-type vacuole membrane is the organism- appropriate child term and is supported by the same fungal MON1 subfamily placement. Proposed replacements: fungal-type vacuole membrane |
| GO:0006623 protein targeting to vacuole | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT places protein targeting to vacuole at the fungal PTN000989606 ancestor, seeded by the experimentally characterized S. cerevisiae MON1. Reason: The IBA is aligned with the fungal-specific PAINT source PTN000989606. In S. cerevisiae, Mon1 and Ccz1 are required for delivery through multiple vacuole-trafficking pathways, and the PTHR13027:SF7 placement supports inheritance of the same vacuolar protein-delivery role by C. albicans MON1. Supporting Evidence: PMID:14662743 Both Mon1 and Ccz1 are required for protein delivery through the Cvt pathway and other vacuole trafficking processes including the CPY and ALP pathways and endocytosis |
| GO:0006623 protein targeting to vacuole | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR004353 identifies the MON1/SAND family and maps it to protein targeting to vacuole. Reason: The InterPro family assignment is consistent with the Q5A723 PTHR13027:SF7 fungal MON1 placement and with the PAINT protein-targeting annotation at the fungal PTN000989606 node. |
| GO:0016192 vesicle-mediated transport | IEA GO_REF:0000002 | MODIFY | Summary: The three FUZ/MON1/HPS1 longin-domain InterPro entries support a conserved membrane-trafficking role but are broader than the MON1-specific vacuolar delivery role already asserted for Q5A723. Reason: Vesicle-mediated transport is true but generic for longin-domain membrane-traffic factors. For fungal MON1, late endosome-to-vacuole transport via the MVB sorting pathway is the supported descendant process that reflects Mon1-Ccz1 action after cargo entry into the endolysosomal system and before vacuole fusion. Proposed replacements: late endosome to vacuole transport via multivesicular body sorting pathway |
| GO:0032585 multivesicular body membrane | IEA GO_REF:0000044 | ACCEPT | Summary: The UniProtKB-SubCell row maps the conserved MON1 localization at multivesicular body or prevacuolar endosome membranes. Reason: The endosomal component of the localization is consistent with the conserved role of Mon1-Ccz1 in the Rab5-to-Rab7 transition during endosome maturation and with the C. albicans protein's placement in the fungal MON1 subfamily. Supporting Evidence: file:CANAL/MON1/MON1-uniprot.txt SUBCELLULAR LOCATION: Endosome, multivesicular body membrane PMID:24413168 our data indicate that Mon1–Ccz1 acts primarily at endosomes and its interaction with HOPS might create an additional GEF microdomain on vacuoles |
| GO:0035658 Mon1-Ccz1 complex | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT places Candida MON1 in the conserved Mon1-Ccz1 complex at the opisthokont PTN000315023 ancestor, with fungal, fly, worm, and human experimental descendants supporting the complex assignment. Reason: Mon1 is a defining subunit of the Mon1-Ccz1 Rab7 GEF complex. The broad PAINT placement is appropriate because the complex and the Rab7/Ypt7 GEF function are conserved from fungi to animals, and Q5A723 remains in the MON1 branch of PTHR13027. Supporting Evidence: PMID:14662743 Biochemical characterization indicates that Ccz1 and Mon1 are needed for the Cvt pathway during the fusion stage, and the two proteins appear to be assembled in a stable protein complex. |
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